Exploitation of these vulnerabilities could cause an interruption of presence services. Cisco Unified Presence contains two DoS vulnerabilities that involve the processing of SIP messages. Each vulnerability is triggered by a malformed SIP message that could cause a critical process to fail, which could result in the disruption of presence services. All SIP ports (TCP ports 5060 and 5061, UDP ports 5060 and 5061) are affected.

The first SIP DoS vulnerability is documented in Cisco bug ID CSCtd14474 and has been assigned the CVE identifier CVE-2010-2839. This vulnerability is fixed in Cisco Unified Presence versions 6.0(7) and 7.0(8). The second SIP DoS vulnerability is documented in Cisco bug ID CSCtd39629 and has been assigned the CVE identifier CVE-2010-2840. This vulnerability is fixed in Cisco Unified Presence versions 6.0(7) and 7.0(8).

Workaround:
There are no workarounds for the vulnerabilities described in this advisory.

It is possible to mitigate these vulnerabilities by implementing filtering on screening devices and permitting access to TCP ports 5060 and 5061 and to UDP ports 5060 and 5061 only from networks that require SIP access to Cisco Unified Communications Manager servers. Additional mitigation techniques that can be deployed on Cisco devices within the network are available in the Cisco Applied Mitigation Bulletin companion document for this advisory:
http://www.cisco.com/warp/public/707/cisco-amb-20100825-cucm-cup.shtml